Wednesday, April 13, 2005

Can God actualize any possible world he wants?

In one of the earliest blogs on this blog when I first started blogging, I blogged a blog about Alvin Plantinga's solution to the deductive problem of evil. Well, before you run off and read it, I just want to say that having looked at it a lot closer and having written a paper about it, I'm afraid I grossly oversimplified his argument to the point of almost mischaracterizing it. So scratch that.

I'm not going to explain his whole argument here, because I'm trying to keep these blogs short enough to be light reads, but I want to take a stab at explaining the part I mentioned yesterday that I had such a hard time understanding. I'm still not totally sure I understand it, but I'm going to take a stab at it.

This is the part where Plantinga argued that there are possible worlds an omnipotent God cannot actualize. I'll leave it to you to find out what possible world semantics is all about. Maybe some day I'll write a blog about it.

By the law of excluded middle, one of the follow two counterfactuals must be true:

1. If it is actual that Shi goes to Jason's house, then Shi will kiss Jason.

2. If it is actual that Shi goes to Jason's house, then Shi will not kiss Jason.

We may not know which of these two counterfactuals are true, but we know at least one of them is true.

There are possible worlds in which Shi goes to Jason's house and kisses him, and there are also possible worlds in which Shi goes to Jason's house and does not kiss him. Nothing is incoherent about either scenario. (Of course there are also possible worlds in which Shi doesn't go to Jason's house at all, but who cares?)

Let's assume (1) is true. If (1) is true, then it is not possible to actualize any world in which Shi goes to Jason's house but does not kiss him. If any world were actualized in which Shi goes to Jason's house, then it would be a world in which Shi goes to Jason's house and kisses him, because we've already stipulated by assuming (1) that if it were actual that Shi goes to Jason's house, then Shi would kiss him. Since (1) is true, God can only actualize those possible worlds in which Shi goes to Jason's house and kisses him. He cannot actualize any possible world in which Shi goes to Jason's house but does not kiss him, because that would lead to a situation in which Shi both kisses him and does not kiss him, which is a contradiction.

If you assume (2) is true, you get the same result. There would be possible worlds that God could not actualize. Since we know by the law of exluded middle that either (1) or (2) is true, it follows that there are possible worlds that God cannot actualize even if he is omnipotent.

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